Handbook of Information Security Management
(Publisher: CRC Press LLC)
Author(s): Hal Tipton and Micki Krause, Consulting Editors
ISBN: 0849399475
Publication Date: 01/01/98

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Technical Safeguards

These are the hardware and software controls to protect the LAN and WAN from unauthorized access or misuse, help detect abuse and security violations, and provide security for LAN applications. Technical safeguards include user identification and authentication, authorization and access controls, integrity controls, audit trail mechanisms, confidentiality controls, and preventive hardware maintenance controls.

User Identification and Authentication

User identification and authentication controls are used to verify the identity of a station, originator, or individual prior to allowing access to the system or to specific categories of information within the system. Identification involves the identifier or name by which the user is known to the system (e.g., a user identification code). This identifying name or number is unique, is unlikely to change, and need not be kept secret. When authenticated, it is used to provide authorization/access and to hold individuals responsible for their subsequent actions.

Authentication is the process of “proving” that the individual is actually the person associated with the identifier. Authentication is crucial for proper security; it is the basis for control and accountability in a system. Following are three basic authentication methods for establishing identity.

Something Known by the Individual. Passwords are presently the most commonly used method of controlling access to systems. Passwords are a combination of letters and numbers (or symbols), preferably comprised of six or more characters, that should be known only to the accessor. Passwords and log-on codes should have an automated expiration feature, should not be reusable, should provide for secrecy (e.g., nonprint, nondisplay feature, encryption), and should limit the number of unsuccessful access attempts. Passwords should conform to a set of rules established by management.

In addition to the password weaknesses, passwords can be misused. For example, someone who can electronically monitor the channel may also be able to “read” or identify a password and later impersonate the sender. Popular computer network media such as Ethernet or token rings are vulnerable to such abuses. Encryption authentication schemes can mitigate these exposures. Also, the use of one-time passwords has proven effective.

Something Possessed by an Individual. Several techniques can be used in this method. One technique would include a magnetically encoded card (e.g., smart cards) or a key for a lock. Techniques such as encryption may be used in connection with card devices to further enhance their security.

Dial-back is a combination method where users dial in and identify themselves in a prearranged method. The system then breaks the connection and dials the users back at a predetermined number. There are also devices to determine, without the call back, that a remote device hooked to the computer is actually an authorized device.

Other security devices used at the point of log-on and as validation devices on the LAN server include port-protection devices and random number generators.

Something About the Individual. These would include biometric techniques that measure some physical attribute of a person such as a fingerprint, voiceprint, signature, or retinal pattern and transmits the information to the system that is authenticating the person. Implementation of these techniques can be very expensive.

Authorization and Access Controls

These are hardware or software features used to detect and/or permit only authorized access to or within the system. An example of this control would be the use of access lists or tables. Authorization/access controls include controls to restrict access to the operating system and programming resources, limits on access to associated applications, and controls to support security policies on network and Internetwork access.

In general, authorization/access controls are the means whereby management or users determine who will have what modes of access to which objects and resources. The who may include not only people and groups, but also individual PCs and even modules within an application. The modes of access typically include read, write, and execute access to data, programs, servers, and Internetwork devices. The objects that are candidates for authorization control include data objects (directories, files, libraries, etc.), executable objects (commands, programs, etc.), input/output devices (printers, tape backups), transactions, control data within the applications, named groups of any of the foregoing elements, and the servers and Internetwork devices.

Integrity Controls

Integrity controls are used to protect the operating system, applications, and information in the system from accidental or malicious alteration or destruction, and provide assurance to users that data have not been altered (e.g., message authentication). Integrity starts with the identification of those elements that require specific integrity controls. The foundations of integrity controls are the identification/authentication and authorization/access controls. These controls include careful selection of and adherence to vendor-supplied LAN administrative and security controls. Additionally, the use of software packages to automatically check for viruses is effective for integrity control.

Data integrity includes two control mechanisms that must work together and are essential to reducing fraud and error control. These are (1) the well-formed transaction, and (2) segregation of duties among employees. A well-formed transaction has a specific, constrained, and validated set of steps and programs for handling data, with automatic logging of all data modifications so that actions can be audited later. The most basic segregation of duty rule is that a person creating or certifying a well-formed transaction may not be permitted to execute it.

Two cryptographic techniques provide integrity controls for highly sensitive information. Message Authentication Codes (MACs) are a type of cryptographic checksum that can protect against unauthorized data modification, both accidental and intentional. Digital signatures authenticate the integrity of the data and the identity of the author. Digital signature standards are used in E-mail, electronic funds transfer, electronic data interchange, software distribution, data storage, and other applications that require data integrity assurance and sender authentication.

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